Estimation Of National Economic Benefits Using The National Water Pollution Control Assessment Model To Evaluate Regulatory Options For Concentrated Animal Feeding Operations.

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EPA is revising the National Pollutant Discharge Elimination System (NPDES) program regulations and the effluent limitation guidelines (ELGs) for concentrated animal feeding operations (CAFOs). For this report, EPA's contractor, RTI, applied the National Water Pollution Control Assessment Model (NWPCAM) to estimate national economic benefits to surface water quality resulting from implementation of new regulations for CAFOs. NWPCAM is a national-scale water quality model for simulating the water quality and economic benefits that result from various water pollution control policies. NWPCAM is designed to characterize water quality for the nation's network of rivers and streams and, to a more limited extent, its lakes. NWPCAM is able to translate spatially varying water quality changes resulting from different pollution control policies into terms that reflect the value individuals place on water quality improvements. In this way, NWPCAM is capable of deriving economic benefit estimates for scenarios for regulating CAFOs.Economic benefits associated with the various AFO/CAFO scenarios are calculated using two estimation methods. The first is based on the Vaughn Water Quality Ladder (WGL), which calculates changes in water quality use-support (i.e., boatable, fishable, swimmable) and the population benefitting from the changes. The second method uses a six-parameter Water Quality Index (WQI6), which represents a composite measure of water quality. Benefits are calculated for each state at the local and nonlocal scales. Local benefits represent the value that a state population is willing to pay for improvements to waters within the state. Nonlocal benefits represent the value that a state population is willing to pay for improvements to waters in all other states in the conterminous 48 states.